Los Angeles , California -LRB- CNN -RRB- -- A judge has delayed the preliminary hearing for Dr. Conrad Murray , charged in Michael Jackson 's death , until early next year because more investigation is being done and some prosecution witnesses wo n't be available until then .

The hearing , in which prosecutors will try to convince the judge there is probable cause to hold a trial , was expected to start in October .

Murray sat silently in front of the judge at Monday 's court appearance , while Jackson 's elderly parents watched from the second row .

Judge Michael Pastor said he `` wanted to expedite '' the case , but he understands it will take more time for each side to prepare .

The preliminary hearing , which is estimated to take two or three weeks , is now scheduled to start on January 4 , Pastor said .

Dozens of Michael Jackson fans , angry about the pop star 's death , gathered outside the courthouse Monday . A handful of them were allowed inside to witness the proceedings .

Murray is charged with involuntary manslaughter in Jackson 's death , which the Los Angeles County coroner ruled was from an overdose of propofol , a powerful anesthesia used to put surgical patients to sleep .

Murray , hired as Jackson 's personal doctor while the singer rehearsed for his comeback concerts , admitted giving him propofol as a sleep aid . But Murray 's lawyer said the amount was much smaller than what was found in Jackson 's body during the autopsy .

`` The fact -LSB- of the way -RSB- that he died was a mystery a year ago , and still is , '' Houston attorney Ed Chernoff told CNN in an exclusive interview recently .

Members of Jackson 's family have attended each hearing since Murray 's arrest in February .

When brother Jermaine Jackson left the last hearing in June , he indicated some of them were not satisfied with the case against Murray .

`` Dr. Murray 's the fall guy , '' Jermaine Jackson said after the hearing . `` This is bulls -- t. ''

California authorities announced last month that seven other doctors and a nurse who treated Jackson will not face criminal prosecution in connection with the singer 's death .

Pastor denied a request by the state medical board to order Murray to stop practicing medicine as a condition of his bond while he awaits trial . His lawyer said he has no California patients , although he continues to treat patients in Nevada and Texas .

Jackson fans have organized protests at each hearing , taunting Murray as he enters and departs the courthouse .

One fan website said they would follow Murray `` into the streets '' after Monday 's hearing with banners on an overpass of the Hollywood Freeway .

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The preliminary hearing had been expected to begin in October

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The prosecution and defense both said they needed more time to prepare

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Dr. Murray is charged with involuntary manslaughter

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Michael Jackson 's parents sat together at Monday 's hearing